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Online Calorie Calculator
Calorie Calculator estimates your daily calorie needs for weight loss, maintenance, or gain from your stats and activity level — plus a joule converter.
| WEIGHT (lb/week, kg/week) | REQUIRED DAILY CALORIES (Cal/Day) | PERCENTAGE | |
|---|---|---|---|
|
Extreme Weight Loss |
-2 | 1,626 | 62% |
|
Weight loss |
-1 | 2,126 | 81% |
|
Mild weight loss |
-0.5 | 2,376 | 90% |
|
Maintain weight |
0 | 2,626 | 100% |
|
Mild weight gain |
+0.5 | 2,876 | 110% |
|
Weight gain |
+1 | 3,126 | 119% |
|
Extreme Weight gain |
+2 | 3,626 | 138% |
Result
9000 J = 2151.05 cal
2000 cal = 8368 J
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What Is This Tool?
The Calorie Calculator estimates how many calories you need each day based on your gender, age, height, weight, and activity level. It calculates your basal metabolic rate using one of three formulas — Mifflin-St Jeor, Revised Harris-Benedict, or Katch-McArdle (which uses your body fat percentage) — then multiplies by an activity factor to produce a seven-row table of daily calorie targets, from extreme weight loss through maintenance to extreme gain. Each target lists the weekly weight change and its percentage of your maintenance calories. A second tab provides a simple joules-to-calories converter, and you can switch between metric and imperial units or download the result as a PDF.
How to Use This Tool?
- On the Calculator tab, set your gender and enter age, height, and weight.
- Pick your activity level and choose a BMR formula, adding body fat % for Katch-McArdle.
- Click Calculate to see daily calorie targets for each weight goal.
- Use the Converter tab to switch values between joules and calories.
Key Features
- Estimates daily calorie needs from gender, age, height, weight, and activity level.
- Offers three BMR formulas — Mifflin-St Jeor, Revised Harris-Benedict, and Katch-McArdle with body fat percentage.
- Shows a seven-row table of targets from extreme loss through maintenance to extreme gain.
- Lists the weekly weight change and the percentage of maintenance calories for each target.
- Includes a joules↔calories converter, a metric/imperial toggle, and PDF download.
Examples
- A 30-year-old man at 182 cm and 80 kg with moderate activity maintains on about 2,626 cal/day (Mifflin-St Jeor).
- That same profile shows roughly 2,126 cal/day for a 1 kg-per-week loss — about 81% of maintenance.
- Switching to Katch-McArdle uses your body fat percentage instead of age and height.
- On the Converter tab, 9,000 J equals about 2,151.05 cal.
Common Use Cases
- Setting a daily calorie target for losing, maintaining, or gaining weight.
- Comparing how different BMR formulas estimate your needs.
- Planning a weekly weight-change goal at a sustainable pace.
- Adjusting intake estimates to match your activity level.
- Converting energy values between joules and calories.
Tips & Best Practices
- Measure height and weight accurately, since they drive the BMR estimate.
- Choose the activity level that matches a typical week, not your most active day.
- Use Katch-McArdle only when you have a reliable body fat percentage.
- Treat the targets as starting points and adjust based on real-world results.
- Favor the milder loss or gain rows for a more sustainable pace.
Limitations
- Results are formula-based estimates and can't account for individual metabolism, health conditions, or medications.
- It isn't medical or nutritional advice and shouldn't replace a professional plan.
- Activity multipliers are broad approximations, so real needs may differ.
- Nothing is saved between sessions — only the current result can be exported as a PDF.
Frequently Asked Questions
- How does it estimate my calorie needs?
- It calculates your BMR with the formula you choose, then multiplies by an activity factor to estimate daily calories.
- What's the difference between the BMR formulas?
- Mifflin-St Jeor and Revised Harris-Benedict use age, height, and weight; Katch-McArdle uses your body fat percentage instead.
- What do the percentages mean?
- Each target is shown as a percentage of your maintenance calories, where 100% is maintenance.
- Can it convert between joules and calories?
- Yes — the Converter tab translates values in both directions.
Key Terminology
- Basal Metabolic Rate (BMR)
- The calories your body burns at rest to maintain basic functions.
- Maintenance calories
- The daily intake that keeps your weight stable, shown as 100% in the table.
- Activity factor
- A multiplier applied to your BMR to reflect how active you are.
- Mifflin-St Jeor
- A widely used BMR formula based on weight, height, age, and gender.
- Katch-McArdle
- A BMR formula that uses lean body mass derived from your body fat percentage.